Geraniums are versatile blooming plants that will grow in flowerbeds, hanging baskets, patio containers or window boxes. With a minimal level of care and plenty of bright sunshine, geraniums will continue to provide colorful blooms from late spring until the first freeze in autumn. Start your geraniums off on the right foot with a good feeding, then fertilize the plants regularly for the biggest, brightest blooms.
Provide fertilizer and rich organic matter at planting time. Spread 3 to 4 inches of compost, leaf mold, ground bark or manure on top of the soil, along with a good quality fertilizer. Use a granular fertilizer with a ratio such as 5-10-15 applied at a rate of approximately 1 tsp. for every square foot of planting area. Spade the organic matter and granular fertilizer thoroughly into the top 8 to 10 inches of soil.
Fertilize your geraniums every four to six weeks throughout the growing season. Use an evenly balanced granular fertilizer with a ratio such as 8-8-8 applied at a rate of 1 tsp. per square foot of planting area. Sprinkle the fertilizer evenly around the plant, but don’t allow it to contact the leaves.
Fertilize containerized geraniums every two to three weeks, using a liquid fertilizer for blooming plants. Mix the fertilizer solution according to the recommendations on the container, as liquid fertilizers will vary. Alternatively, use an evenly balanced granular fertilizer instead of a liquid fertilizer. Apply 1 tsp. fertilizer for a 12-inch pot. Reapply every three to four weeks.
Apply fertilizer to moist soil. Water deeply immediately after adding fertilizer so the fertilizer will be evenly absorbed into the soil around the roots of the plant.